Thioalkanoate chemical intermediates

ABSTRACT

COMPOUNDS OF THE FORMULA   R&#39;&#39;-O-CH2-N(-R&#34;)-CO-W-S-CO-R&#39;&#39;&#34;   WHEREIN R&#39;&#39; AND R&#34; ARE HYDROGEN OR LOWER ALKYL, W IS AN AKLYLENE LINKING GROUP WHICH MAY CONTAIN A HYDROXYL OR ETHERE GROUP AND R&#34;&#39;&#39; IS A HYDROXYCARBYL GROUP OF 1-10 CARBON ATOMS, ARE USEFUL AS INTERMEDIATES IN FORMING CELLULOSIC POLYMER MODIFIERS.

United States Patent Int. Cl. C070 153/07 U.S. Cl. 260-455 R 2 ClaimsABSTRACT OF THE DISCLOSURE Compounds of the formula 0 0 a ll R-O-CHz-N-Ws-0R'" wherein R and R" are hydrogen or lower alkyl, W is an alkylenelinking group which may contain a hydroxyl or ether group and R" is ahydrocarbyl group of 1-10 carbon atoms, are useful as intermediates in.forming cellulosic polymer modifiers.

This application is a division of application Ser. No. 665,289, filedSept. 5, 1967, now US. Pat. No. 3,485,815, which in turn was acontinuation-in-part of application Ser. No. 347,365, filed Feb. 26,1964, now abandoned.

This invention relates to a method of modifying cellulosic polymers andmore particularly to a method of modifying a material comprisingcellulosic polymers. The invention also relates to organic reactantswhich are suitable for treating cellulosic polymers in accordance withthe method of the present invention.

Wool fibers consist primarily of long chain polymers which arecrosslinked by disulfide radicals. These disulfide crosslinks impartcertain useful properties to the wool fibers.Thus, for example thedisulfide crosslinks can be opened, the fibers may be given a desiredconfiguration, and the crosslinks then reformed in order to stabilizethe fibers in their new configuration. Permanent creasing of woolfabrics is one important commercial utilization of the naturallyoccurring disulfide linkages.

In view of the widely accepted importance of disulfide crosslinks inimparting desirable properties to wool fibers, it is apparent that theintroduction of such crosslinks into cellulosic polymers is a desirableobjective. The disulfidemercaptan system is especially desirable due tothe ease of conversion of one form to the other.

In addition to the advantages resulting from the re- 'versibility of thedisulfide-mercaptan linkage, the modification of cellulosic polymers byintroduction of this system is important for another reason. Thereactivity of cellulosic polymers is somewhat limited since the hydroxylgroups provide the only reactive sites. Since mercapto groups are muchmore reactive than hydroxyl groups in many organic reactions, theintroduction of mercapto groups into cellulosic polymers increases thereactivity of the cellulose in organic reactions such as alkylation andgraft polymerization.

In view of the foregoing, it is an object of the present invention toprovide a method of modifying a material comprising cellulosic polymermolecules by introducing disulfide or mercapto radicals into thecellulosic polymer molecules.

It is another object of this invention to provide organic reactantsincluding a mercapto radical or a disulfide "Ice radical for use intreating cellulosic polymer molecules in accordance with the method ofthis invention.

Briefly stated, one embodiment of the present invention is the method ofmodifying a material comprising cellulosic polymer molecules comprisingthe steps of providing an organic reactant embodying (A) acellulosereactive group, such as formyl (CHO), or an N- methylolcarbamoyl radical having the formula:

wherein R and R" are hydrogen or substituted or unsubstitutedhydrocarbyl, such as substituted or unsubstituted alkyl of from 1 to 4carbon atoms;

and (B) a sulfur-containing group such as a disulfide radical or amercapto radical in a free or protected form, as acylthio; saidcellulose-reactive group and said sulfurcontaining group being separatedby a divalent organic linking radical containing at least oneintralinear carbon; and treating said material with said organicreactant in the presence of an acidic catalyst.

The organic reactants can be represented by the general formula:

wherein Z is said cellulose-reactive group; W is said linking radical; Xis mercapto or protected mercapto, e.g., acylthio, or a disulfide group;and n is an integer having a value of 1 when X is free or protectedmercapto and a value of 2 when X is disulfide.

When n in Formula I has a value of 2, the ZW-groups may be the same ordifferent.

As noted above, the cellulose-reactive group can be formyl.Alternatively it may be a group which, under the reaction conditions(i.e., in an acidic medium) yields a formyl radical, such as an aldehydeacetal group of the formula:

CHtOR) I wherein R is substituted or unsubstituted hydrocarbyl, such assubstituted or unsubstituted alkyl having 1 to 4 carbon atoms.

Compounds having the aldehyde acetal grouping, when subjected to theconditions hereinafter described for the treatment of cellulose, formthe formyl group which then reacts with the celluose. This conversion ofacetal to aldehyde is illustrated by the following equation, employing amercapto acetal for purpose of illustration:

R0 CHWSH Hii-WSH 2ROH(A) j: I H2O Accordingly, as employed in thespecification and claims, the term formyl is intended to embrace groupssuch as aldehyde acetal groups which yield formyl groups in aqueousacidic media.

The sulfur-containing radicals represented by X in Formula I serve toprovide sites, which may be opened or closed by selection ofoxidation-reduction conditions. Thus, disulfide-modified cellulosicpolymers can be reduced to the mercapto form, and the latter can beoxidized to produce the disulfide as shown by schematic Equation B inwhich Cell represents a cellulosic polymer and B denotes a connectingradical.

(B) oxidizing reducing Thus, if a mercapto type of reactant is used toform disulfide crosslinks in accordance with the present method, onlyone cellulose-reactive functional group need be present in the reagentmolecule. The crosslink between cellulosic polymers in such instance isformed by reaction of two mercapto-containing chains to form a disulfidelinkage.

When employing the mercapto type of reactant it is frequently desirableto have the mercapto group in a protected form to prevent prematuredisulfide formation by oxidation due to atmospheric oxygen which may bepresent during pregnation of the reactant, or during treatment ofcellulose. A suitable protective form of the mercapto group is theacylthio group of the formula:

1| SCRIII (IV) wherein R is substituted or unsubstituted hydrocarbylsuch as substituted or unsubstituted alkyl or aryl having from 1 tocarbon atoms.

The acylthio group is inafi'ected by the acidic media employed duringthe reaction of the organic reactant with cellulose, but the acylprotecting group may be readily removed (i.e., the acylthio group isconverted to mercapto), by treatment with base.

If a disulfide-containing reactant is used to form disulfide crosslinks,there must be two cellulose-reactive functional groups present. Thecrosslink in this case is formed by reaction of one cellulose-reactivefunctional group with a first cellulosic polymer molecule, and reactionof the second group with a second cellulosic polymer molecule.

The cellulose-reactive functional group must be separated from thesulfur-containing radical by at least one carbon atom to preventsplitting of the compound at this juncture. Preferably, thecellulose-reactive functional group should be separated from thesulfur-containing radical by a substituted or unsubstituted alkyleneradical having from 1 to 4 carbon atoms.

Substituents which may be present on the various groups defined aboveinclude any substituent which is inert under the reaction conditions.Particularly desirable substituents are those wherein oxygen is presentin the form of a hydroxyl group or an ether linkage, which improve thesolubility of the organic reactant in water and make them moreattractive for commercial utilization.

Some typical examples of organic reactants which are suitable for thepractice of this invention are as follows:

Although most of the above compounds are of the disulfide type, it is tobe appreciated that the mercapto form corresponding to the disulfidecompounds may be formed by reduction, and those mercapto compounds areconsidered included in the foregoing illustrative list.

Compounds (1)-(6) contain the N-methylol amide type ofcellulose-reactive functional group; compounds (7) and (8) contain thealdehyde acetal type of group; and compounds (9) and (10) contain thealdehyde type of group.

In compounds (3) and (10) the cellulose-reactive function groups areseparated from the sulfur-containing groups .by a radical containing anether linkage. In compounds (4) and (9) there is a hydroxyl substituent.

Each of the disulfides discussed above is symmetrical that is, theportions of the molecule on either side of the sulfur atoms areidentical. The present invention is intended cover unsymmetricaldisulfides as well, and these may be made, for example, by mildoxidation of a mixture of two mercapto compounds.

Typical temporarily protected forms of the thiols which may be used asorganic reactants in the practice of this invention are as follows:

HOCHzlIIC CHzS CH3 C2H OCHNC|CH S C CaH5 (13) II II ClHgOCHzIITC (ilH SC 0:11

CH3OCHCH2SC CH3 O O H I; HO CIIH S COH5 Sulfur-containing compounds ofthe N-methylol amide type can be prepared by conventional techniques.The preparation of one such compound (Compound 1) is illustrated asfollows:

Example 1 First an intermediate having the following formula wasprepared:

To this end 64 grams of sulfur were added at room temperature to 240grams of Na S-9H O dissolved in 2000 ml. of water while stirring. Thismixture was warmed up to 70 C. and kept at this temperature until thesulfur went into solution. Then the solution was cooled to roomtemperature and 284 grams (4 moles) of acrylamide dissolved in 400 ml.water were allowed to drip into this solution over a period of 30minutes. The reaction was slightly exothermic. After half of theacrylamide solution was added, a crystalline product started toprecipitate. After the addition of acrylamide was completed, thereaction mixture was stirred for additional 30 minutes, then filtered.The crude product was washed with water, dried and recrystallized from4500 ml.

ethanol. The weight of recrystallized product was 195 grams,corresponding to a 47% yield.

The melting point of the product was 160 C.-162 C., the sulfur contentwas 31.03% by weight and the nitrogen content 13.09% by weight. Thetheoretical sulfur content of the above intermediate is 30.80% and thetheoretical nitrogen content is 13.45%.

In the second part of this procedure 156 grams (0.75 mole) of theintermediate was slurried in 1900 ml. of water. The pH of the aqueousslurry was adjusted to 8.0-8.2 by adding a few drops of N NaOH. Theaqueous slurry was heated to 65 C. with stirring. A clear solution wasobtained. 123 grams of 37% aaqueous formaldehyde solution (1.5 moles)were allowed to drip into this solution over a period of 1 hour. Afterstirring for hours, 73% conversion (determined from the decrease in freeformaldehyde content of the reaction mixture by using hydroxylaminehydrochloride) was achieved. By partially distilling off the water underreduced pressure, the reaction mixture was concentrated to 300 grams.After chilling in the refrigerator overnight, 1800 ml. methyl ethylketone were added. A white crystalline product was obtained andfiltered. It was recrystallized from 98 grams corresponding to a 48.5%yield, M.P.: 129-132" C. The product was slightly soluble in water andvery soluble in mixture of water with organic solvents.

S content: 23.90% (Theor. 23.88%)

N content: 10.53% (Theor. 10.45%) OH content: 12.31% (Theor. 12.70%).

The procedure outline in Example 1 can be generally employed for theconversion of dithioamides of the formula:

(where W is defined as in Formula II) to the correspondingbis(N-methylol) amides:

In the presence of excess alcohol [R'OH, where R is defined as inFormula I] and by suitable changes in the solution pH during thereaction with formaldehyde, the corresponding bisalkoxymethyl amides:

R--0CHgNH-( i(W)SS(W)ii-NHCH2OR (VII) can also be obtained.

If N-substituted amides:

o o g H HN (W)-SS(W)ONH R (VIII) [where R" and W are defined as above]are used as the intermediates, the reaction with formaldehyde will occuron the free hydrogen and the corresponding N-subtsituted reactants willbe obtained.

The intermediate dithioamides required for the preparation of the newreactants can be prepared from the corresponding unsaturated compoundsas shown in Example 1, or by converting a haloamide to a mercaptan, forexample:

or by reacting a sulfur containing acid chloride with ammonia or anamine, for example:

Preparation of a preferred temporarily protected reactant,2-(acetylthio)-N-(hydroxymethyl) acetamide is illustrated by thefollowing example:

Example 2 ll ll HOCH2IIICCH2- S 0 CH3 A total of 308 grams (4.05 moles)of thioacetic acid was added gradually to a solution of 266 grams ofpotassium hydroxide (4.05 moles) in 2 liters of ethanol while nitrogenwas bubbled through the solution. Then a total of 500 grams (4.05 moles)of 2-chloro-N-(hydroxymethyl) acetamide was added to the solution ofpotassium thioacetate while the temperature of the reaction mixture waskept somewhat under 50 C. Stirring was continued until the reactionmixture cooled to room temperature. By-product potassium chloride wasremoved by filtration and dried. Its weight was 303 grams (theoretically302 grams). Ethanol was evaporated from the filtrate, leaving 662 gramsof solid (theoretically 660 grams) of Z-(acetylthio)-N-(hydroxymethyl)acetamide, which upon being recrystallized from ethyl acetate in 72%yield, melted at 93 to 965 C. (104 to 105 C. after recrystallizationfrom benzene.) Analysis of bound formaldehyde indicated a purity of96.2%, (17.7% found compared with 18.4% required for C H NO S).Absorption bands in the infrared spectrum were those expected for thestructure shown above.

This procedure is not limited to thiol S-esters of N-(hydroxymethyl)amides, but can be applied generally to aldehydes, acetals, orN(oxymethyl) alkanamides which have a halogen atom (chlorine, bromine oriodine) bonded to the carbon atom which ultimately is to hold a mercaptogroup or a dithio group. An alkali metal salt of a thiocarboxylic acidis used to effect a replacement reaction. Thus, the acetylthio group canbe provided by potassium thioacetate and the benzoylthio group can beprovided by sodium thiobenzoate.

In general, the organic reactants of this invention are utilized in asolvent, preferably water. Assuming the material to be modified is acotton fabric, a solution of one of the organic reactants is applied tothe fabric by dipping, spraying, padding or other suitable manner. Theprocess requires acidic conditions, or in other words, the presence ofan excess of hydrogen ions. It is believed that the reaction of thealdehyde type of compound with a collulosic polymer molecule is asfollows:

srr

Cell-O-CH-O-Cell 1120 bmon a The treatment of cellulosic polymermolecule with compounds including an N-methylol amide radical proceedsgenerally as follows:

H H (G) Although the solvent utilized to form the solution of thesulfur-containing reactant is preferably water, when the solubilities ofthe reactants in water are not sufficient for the desired purposes, thewater may be mixed with a compatible organic solvent, or an organicsolvent alone may be used.

The amount of the sulfur-containing reactant to be applied to thecellulosic material generally should be in the range of from 2% to 30%,based on the weight of the cellulosic polymer molecules in the materialbeing treated. Of course, the particular strength which is selected willbe based on the extent of modification which is required for theparticular properties which are desired. It has been determined that theuse of from 5% to of sulfur-containing reactant, based on the Weight ofthe cellulosic polymer molecules, is suflicient to impart excellentproperties.

As indicated, the treatment of cellulosic polymer molecules with thesulfur-containing reactants of this invention must be conducted underacidic conditions. Acidic catalysts which are suitable for use with thepresent invention include the ammonium salts of mineral acids such ashydrochloric, sulfuric, phosphoric, perchloric and nitric; amine saltsof mineral acid; the chlorides and nitrates of zinc and magnesium; acidfluoride salts; zinc fluoroborate and others of this type. In additionto the above salts, nonvolatile acids of moderate strength such oxalicacid and sodium hydrogen sulfate may also be employed.

Some of the above acidic catalysts, such as magnesium chloride areacid-forming and provide acidic conditions upon heating. When suchcatalysts are used, the treated material must be heated to thetemperature level necessary for production of the requisite acidconditions.

If the acidic catalyst is of the type that does not require heating toform hydrogen ions, for example, those catalysts which form hydrogenions upon hydrolysis or ionization in a solvent, the catalytic activityis generally controlled by appropriate choice of the pH of the treatingsolution. In such instance, the pH of the treating solution should behigher than about 3.5 since the use of acid catalysts yielding asubstantially lower pH may adversely affect the cellulosic materialbeing treated.

The term acidic catalyst as used in this specification and in the claimsappended hereto is intended to include those substances which are acidicper se as well as those compounds or materials which have the latentability to provide acidic conditions in situ, for example, by exposureto elevated temperature.

After treatment with the organic reactant and catalyst, the treatedcellulose is generally dried at a relatively low temperature and thenheated to a higher temperature for a short period of time to acceleratethe reaction between the cellulose and the sulfur-containing reactant.Preferably, the higher temperature step is conducted at temperatures inthe range of 140 C. to 175 C. for a time in the range of about 2 minutesto 10 minutes. Of course, temperatures lower than 140 C. may be usedwith a corresponding increase in the time. 70

The term cellulosic polymer molecule as used herein is intended todenote the cellulose polymer molecules as they occur naturally in theform of cotton, linen and Wood. It is also intended to embrace modifiedcellulose such as regenerated cellulose including viscose, cuprammoniumrayon and saponified cellulose acetate, cellulose film; soluble modifiedcellulose such as hydroxyethyl cellulose and carboxymethyl cellulose;and the like provided the modified polymer molecules contain freehydroxyl groups. The cellulose can be in the form of textile fiberswhich have been manufactured into fabric, or in the form of films,fibers, or yarns. Cellulose fibers may be incorporated into yarns andfabrics together with other textile fibers, and the composite materialmay be treated by the present process. In addition, such naturalcellulosic materials as wood and linen may also be treated in accordancewith the present invention.

Cellulose which has been treated in accordance with this invention isreversibly cross-linkable whereby disulfide linkages can be cleaved byreduction (incorporation of hydrogen) and reformed by oxidation(abstraction of hydrogen). When the modified cellulosic material is inthe reduced or mercapto form the material may be creased or otherwiseshaped and then exposed to a mild oxidizing treatment to restore thedisulfide crosslinks.

Oxidizing agents for forming disulfide crosslinks in the complexcellulosic polymers containing mercapto groups include hydrogenperoxide, sodium perborate, gaseous oxygen with anydrous ferric sulfatein dimethyl sulfoxide [C. G. Overberger et al., J. Am. Chem. Soc., vol.87, 4125-4130 (1965)], and atmospheric oxygen, as well as iodine [R. F.Schwenker et al., Textile Res. 1., vol. 32, 797-804 (1962), and vol. 33,107-117 (1963)].

Reducing agents for rupturing disulfide crosslinks and forming mercaptogroups include alkali and ammonium salts of aliphatic mercaptans such asthioglycolic acid, thioglycerol, mercaptoethanol and the like,neutralized tetrakis (hydroxymethyl) phosphonium chloride, sodiumhydrogen sulfide with sodium sulfite, tributylphosphine, sodiumtetrahydroborate and water, and 1,4-dimercaptothreo-2, 3-butanediol.

In addition, disulfide cleavage may result from simultaneous reductionand oxidation (disproportionation by a base).

The mercapto form of cellulosic derivatives produced by the methods ofthis invention can be further modified to new and useful compositions byalkylation in any of several ways. One such method is by reaction withactivated vinyl compounds, such as acrylonitrile, divinyl sulfone andN-ethylmaleimide. Another is by metathesis, a replacement reaction whichinvolves treating the mercapto-containing polymer with strong base suchas sodium hydroxide, to make the S-sodium derivative, followed byreaction with a halogen-containing compound. For instance, iodoalkanesrequire about 6 hours at C. when used as a 5% by weight solution indimethylformamide free of molecular oxygen. Such as replacement reactionis not confined to haloalkanes, and iodoacetamide, bromoacetaldehydeacetals, and chloroacetonitrile are examples of other compounds whichare suitable.

Whether formed by addition or replacement, the resulting organicsulfides are stable derivatives (sulfur analogues of ethers) In thismanner one can provide modified forms of cellulose in a more facilefashion than by previous techniques or provide forms heretoforeunattainable because of the higher reactivity of the mercapto groups ascompared with cellulosic hydroxyl groups.

The following examples are illustrative of the methods by whichcellulose may be modified in accordance with this invention. In theseexamples, the following test methods and analytical procedures wereemployed:

(1) Crease recovery-Monsanto Test Method ASTM D-1295- T, October 1961.Reported as the sum of the crease recovery angles in the warp andfilling directions (W+F) after one laundering according to AATCC 88 1961T, Test III C-2.

(2) Tear strength. Elmendorf Method ASTM D-l42459. Reported in pounds.

(3) Tensile breaking strength.-One-inch ravelled strip method; ASTMD-1682-59T. Reported in pounds.

(4) Moisture regain-Moisture gained on conditioning (relative humidity65i2% at 21:1 C.) based on the oven-dry weight; ASTM D-629-59T. Reportedin percent.

() Efliciency of utilization of reagent (in percent) (equiv. Wt. ofreagent) (observed wt. gain) (100%) (equiv. Wt. of group of atomsbecoming bonded to polymer) (percent OWF) The reagent was padded on thefabric from an aqueous solution which also contained magnesium chloride(12 to MgCl based on the weight of the reagent) as a catalyst. Afterpadding, the fabric samples were framed to the original dimensions,dried (2 minutes at 65 C.), cured (5 minutes at 150 C.), washedthoroughly, framed, and dried. Data relating to the treatment of thefabric samples and the resulting products are summarized in Table I.

TAB LE 1 Analysis (percent) Reagent, Moisture Weight Calculated 2 Foundpercent regain, gain, Sample OWF percent percent 1 S N S N 1 Correctedfor change in moisture regain. 2 Calculated from the corrected weightgain for the cellulose derivative, Ce1lOCHzNHCOCH2SOOOHa.

(6) Thiol sulfur.-The sample (approximately 0.08 gram) was kept for 5 :1days at room temperature in 25 Total (W+F) crease Warp Warp 100 ml. ofsolution containing 0.0125 gram of N-ethylangle degrees 6332 g?maleimide Sample Dry Wet pounds pound C2Hs A 263 238 38 1. 0 B- 249 24337 1. 0 O=CNC=O C 242 232 39 1.0 D 235 231 37 1.0 HO-OH buifered at pH3.5. Its reaction with thiol groups was de- Example 4 terminedquantitatively from the change in ultraviolet absorbance at 300millimicrons, as described by R. W. Burley and F. W. A. Horden, TextileRes. 1., vol. 27, 6l5-622 (1957).

(7) Disulfide sulfur.-The sample (approximately 0.24 gram) was kept for'24 hours in 25 ml. of nitrogen-flushed water containing 0.020 gram of1,4-dirnercapto-threo-2,3- butanediol Samples of fabric resulting fromtreatment similar to that described in Example 3 were treated undernitrogen with 0.2-normal sodium hydroxide solution at a fabricto-liquorweight ratio of l-to-30 for 30 minutes at room temperature. Then theywere washed thoroughly in succession with water, aqueous 2% acetic acid,again with water, and finally dried. Samples were kept under nitrogenuntil physical testing and analyses were performed. The test results aresummarized in Table H as Sample A, together with similar data obtainedon (B) a fabric sample resulting from treatment similar to thatdescribed in Example 3 so that the nitrogen content was 1.05%, and (C)an untreated specimen of the printcloth.

TABLE II Warp tensile strength, lbs.

W+F crease recovery angle, degrees Percent N Thiol S Form Dry Wet 1. 0l. 85 1. 05 0. 25 Untreated 0 0 The amount of o-dithiane-4,5-diolHOCHCH2S HCOH CH2---S Samples of de-sized, bleached, and un-mercerizedplainweave cotton fabric (commonly known as 80 x 80 printcloth) weretreated with the 2-(acetylthio)-N-(hydroxymethyl)acetamide produced asdescribed in Example 2.

Example 5 Samples of fabric comprising (2-mercaptoacetamido)-methylcellulose produced as described in Example 4 were treated with aneutral, aqueous 3% solution of hydrogen peroxide, with thefabric-to-liquor ratio at 1-to-30 by weight, for 30 minutes at roomtemperature. Then they were washed with water and dried. The resultingproduct comprised cellulose crosslinked through groups which had total(warp plus filling) crease recovery angles of 242 degrees (dry) and 265degrees (wet), a Warp tensile strength of 37 pounds, 0.9% N, and 0.0%thiol sulfur.

Example 6 Samples of fabric comprising (2-mercaptoacetamido)-methyl-cellulose produced as described in Example 4 12 were extractedrepeatedly with dimethyl sulfoxide to reto pH 7.0 with sodium hydroxide,with the fabric-to-liquor place water. Then they were treated at roomtemperaratio at 1-to-30 by weight, for 2 hours at 40 C. Then ture forminutes with a 0.1% solution of anhydrous the samples were washed withwater and dried. The referric sulfate in dimethyl sulfoxide throughwhich a sulting thiol form was then treated with hydrogen pervigorousstream of oxygen was passed. The fabric-tooxide to re-form thecrosslinks. The cycle of cross-link liquor ratio was 1-to-30. At the endof the 30-minute cleavage and reformation was repeated. The data forthis oxidation, the samples were washed with water and dried. series ofexperiments are summarized in Table V, with Data showing the history ofthe sample at each of the SampleAbeing that produced in Example 5.

TABLE V W-i-F crease Warp recovery angle, deg. tensile PercentDistinguishing strength, Sample composition Dry Wet lbs. N Thiols ACross-linked 242 265 37 0.95 0.0 13..-. Thiol 193 255 1.0 0.47 0.... 233269 32 0.9 O. 10 D--. 189 254 31 0. 8 0.21 E Cross-linked 233 269 29 1.00.07

S-ester (A), the thiol (B) and the crosslinked stages are summarized inTable III.

TABLE III W+F crease recovery Warp S angle, deg. tensile strength, N,Total, Tliiol, SS-, Sample Form Dry Wet lbs. percent percent percentpercent Sample 260 249 37 1. 30 2. 48 N one 0. 08 A 192 229 38 2. 25 1.14 None B 184 264 37 2. 28 0. 01 1. 26 C Example 7 Example 9 g i ifabric g g gfiig g igii g z A sample of fabric containingdithiobis(acetamidomethme y u ose F uce a e 1 P yl) crosslinksintroduced by the method of Example 5 was were Posed for of 40 usedwhich had 0.72% nitrogen and 1.56% sulfur by P R; lthls Senes ofexpenments are Sumanalysis. The fabric was padded with an aqueoussolution manze m a e having 0.5 mole of sodium hydrogen sulfide and 0.5mole TABLE IV of sodium sulfite per liter. In order to effect theexchange W+F dry 4" of hydrogen atoms between reactants, the sample wasPeriod 352g; sulfur contentnement heated in steam for 10 minutes. Theaccompanying Table Sam 16 of gi rg s a ng g m: VI records the data onthe modified cellulose in fabric p g form from preparation of theS-ester (A); formation of 52% 32 81?; the thiol form (B); crosslinkingaccording to Example 5 1g g. 3:; 3. 2g (C) and as it was carried throughthree cycles of reduction (acceptance of hydrogen atoms) and oxidation(dehydro- 1 The relatively humidity of the air was 6512% genation toform disulfide crosslinks) (D-I).

TABLE VI W+F crease recovery Warp angle, deg. tensile Percent strength,

Dry Wet lbs. N S

260 243 0 194 247 s 267 279 2 101 232 237 281 164 231 222 261 Th 01 169242 I Cross-linked 211 254 Example 8 Example 10 Samples of fabriccontaining dithiobis(acetamidometh- A sample of fabric identical withSample C of Example yl) crosslinks produced as described in Example 5were 9 was immersed for 2 hours at 40 C. in an aqueous solutreated afternitrogen with an aqueous 20% solution of tion containing 0.5 mole oftributylphosphine per liter to tetrakis(hydroxymethyl)-phosphoniumchloride adjusted cleave the disulfide cross-links. This sample (D) wasthen cross-linked with hydrogen peroxide as described in Example 5(Sample E). Two additional cycles of cleavage with tributylphosphine andoxidation with hydrogen peroxide were performed. (F-I). The results ofthese experiments are summarized in Table VII.

5 history and properties of the modified fabric are sum- TABLE VII W+1Fcrease recovery angle, deg.

Dry W Example 11 A sample of fabric identical with Sample C of Example 9was padded with an aqueous solution composed of 5 marized in theaccompanying Table IX. The increased percentage of nitrogen upontreatment with acrylonitrile indicated that chemical addition occurred.

TAB LE IX W+F crease recovery angle, degrees Total, percent Thiol S,Sample Form Dry Wet N S percent A S-ester 244 245 0. 74 1.4 Trace 13..hiol. 180 203 Unanalyzed 1. 4 C Disulfide 227 276 Unanalyzed Trace DThiol 180 228 0.80 .4 1.4 E Acrylonitrile adduet 206 257 1.16 1.4 11.99

This percentage of thiol sulfur was calculated from the increase inpercentage of nitrogen (the addition of acrylonitrile was notquantitative).

Acrylonitrile-modified products of this nature are heatresistant androt-resistant.

Example 13 The procedure of Example *12 was repeated, except thatdivinyl sulfone was used instead of acrylonitrile. Starting with SampleD of Example 12, data on the history and TABLE VIII W+F crease recoveryWarp angle, deg. tensile Percent strength, Dry W lbs. N S

Example 12 A sample of fabric containing dithiobis(acetamidomethyl)crosslinks introduced by the method of Example properties of themodified fabric are summarized in Table X. The increased percentage ofsulfur upon treatment with divinyl sulfone indicated that chemicaladdition occurred.

TABLE X W+F crease recovery angle, degrees Total, percent Thiol S,Sample Form Dry Wet N S percent D Thi 180 228 0.80 1.4 1.4 E Adduct 194294 0. 74 2.2 "1.6

This percentage of thiol sulfur was calculated from the increase inpercentage of sulfur (the addition of divinyl sulfone was notquantitative).

5 and subsequently reconverted to (Z-mercaptoacetamido) methylcelluloseby the method of Example 9 was padded with an aqueous 1% solution ofsodium hydroxide, and

EXAMPLE 14 A sample of fabric characterized by containing the S- acetylderivative of (Z mercaptoacetamido)methylcelluwithout drying, the paddedfabric was immersed in acryl- 75 lose was prepared by a method similarto that described in Example 3. The fabric so treated had the followingproperform resulted from the l-iodoalkanes, respectively, as

ties: listed in the heading:

N-l 30% [2- (isobutylthio) acetamido] methylcellulose, S-2.48 [2-(penty1thio)acetamido] methylcellulose,

Thiol S-None [2- (dodecylthio) acetamido] methylcellulose, and

[2- octadecylthio) acetamido] methylcellulose.

Data relating to the various sample are summarized in Table XII, whichincludes data on a series of four corresponding samples subsequentlytreated with hydrogen per- Crease Recovery:

Dry247 degrees Wet237 degrees 4 Warp tenslle Strength 1 Pounds oxide asdescribed in Example 5.

TABLE XII Before treatment with H202 After treatment with H202 PercentWarp W-l-F crease recovery Percent Warp W+F crease recovery tensileangle, deg. tensile angle, deg. Wt. Thiol strength, Disulfide Thiolstrength, Sample S-alkyl gain S lbs. Dry Wet S 8 lbs. Dry Wet A CH2OH(CH)2 0. 8 None 28 211 234 0. 17 None 36 213 255 B H2)4OH 1.7 None 35 218259 0. 10 None 35 224 262 C (CH) CH3 4.3 None 35 230 228 0.12 None 37229 258 D (CH2)11CH3 8. 8 0. 06 36 213 224 0. 18 None 30 226 240 Example16 Then, by using a procedure similar to that described in Example 4,the S-acetyl group was replaced by hydrogen, leaving free(Z-mercaptoacetamido)methylcellulose. The sample was stored briefly inan atmosphere of dry nitrogen, and then padded with an aqueous 5%solution of sodium hydroxide to form the S-sodium derivative. The thustreated fabric was immersed for 6 hrs. at 50 C. in a solution consistingof 5 parts by weight of iodoethane and 95 parts by weight ofdimethylformarnide. During the 6-hour period, nitrogen was bubbledthrough the reaction mixture. At the end of the reaction period, thefabric sample was rinsed in dimethylformamide and water, then desiccatedin dry gaseous nitrogen. The resulting S-ethyl derivative was thentreated with hydrogen peroxide by the procedure of Example 5. Datarelating to this sample are The fabric sample in the thiol form ofExample 14 which had been treated with hydrogen peroxide to formdisulfide cross-links was subjected to treatment similar to thatdescribed in Example 8 to reform the thiol groups. That is, the chemicalreactions of Example 8 were applied to the crosslinked or disulfide formto yield (Z-mercaptosummarized in the accompanying Table XI, togetherwith Example 5.

TABLE XIII Before treatment with H202 After treatment with H2O:

Percent Warp W-l-F crease recovery Percent Warp W+F crease recoverytensile angle, deg. tensile angle, deg.

Wt. Thiol strength, Disulfide Thiol strength, Sample S-alkyl gem 8 lbs.Dry Wet S S lbs. Dry Wet E -H l 1.41 38 196 260 0. 84 0.41 37 264 199CzH 0. 1 None 37 212 255 0. 23 None 39 233 245 0. 1 0. 04 36 202 260 0.69 None 36 231 268 0. 1 None 36 208 266 0. 25 None 37 236 262 3. 7 None37 222 240 0. 22 None 35 246 237 7. 0 0. 03 35 214 226 0. 34 None 35 234235 (2-mereaptoaeetamido methylcellulose prepared by the method of Exgnple 8.

asis.

data on the thiol form, both before and after treatment with hydrogenperoxide.

TABLE XI Thiol S-ethyl Before treatment with 15:0

Weight gain, percent 0 0. 2 Thiol S, percent 1.39 None Warp tensilestrength, lbs 39 36 Crease recovery:

Dry, degree"..- 206 206 Wet, degrees-.. 264 252 After treatment with HDisulfide S, percent" 1. 80 0. 12 Thiol S, percent None None Warptensile strength, lbs 32 35 Crease recovery:

Dry, degrees"- 257 203 Wet, degrees--- 278 233 EXAMPLE 15 The procedureof Example 14 was repeated four times, except that each time a differentl-iodoalkane was used in place of iodoethane. The following derivativesin fabric Example 17 Two samples of plain weave cotton fabric (commonlyknown as x 80 print cloth), were treated with disulfide produced asdescribed in Example 1. The disulfide was dissolved in a 1:1 by weightdimethylformamide-water solution which also contained magnesium chlorideto provide acidic conditions. The magnesium chloride was added in theform of a buffered 30% aqueous solution (commercially available underthe name Aerotex Accelerator MX, sold by the American Cyanamid Co.). InTable XIV, the figures under the heading percent MgCI Soln. refer to theweight percent of Aerotex Accelerator MX used in the treating solution.

TABLE XVI Treatin solution percent) High Percent Amine temp.hydrochloride step, Weight Sample Disulfide solution 0.) increase YieldCrease recovery data on samples C and D are set forth The columns headedPercent S and Percent N set forth the weight percent of sulfur andnitrogen contained in the cloth samples after treatment.

fabric samples A and B. in Table XVII.

TABLE XIV Treating solution Percent Percent Percent MgClz weight PercentPercent Percent S/N SIN Sample disulfide 50111.2 increase yield S N act.theor.

A 8.0 6.0 6.5 91 1.26 0. 57 2.22 2.28 B 5. o 3. 75 3. 9 95 0. s2 0. 392. 10 2. 28

The column head Percent Disufide and Percent TABLE XVII MgCl containsthe weight percent of the hsted material in the solutions used to treatsamples A and B. Crease recovery deg ee The column headed Percent WeightIncrease indicates Sample Dry Wet the increase in weight of the finishedsample as compared 0 260 241 to the weight prior to treatment. D 247 233The column headed Percent Yield is an indication of 30 the proportion ofthe disulfide reactant employed which E 1 9 reacts with the sample. P e1 Samples of 80 x 80 printcloth of the same type employed in Example 3were treated with the 3,3-dithiobis[N-(hydroxymethyl) propionamide]produced as described in Example 1. The reagent was padded on the fabricfrom a solution composed of dimethylformamide and water (2:1 by weight)which contained magnesium chloride (15% MgCl based on the weight of thereagent). The pH of the pad bath was varied (7.4, and 3.8 by means ofdilute acetic acid). After padding, the fabric samples were framed tothe original dimensions, dried, cured (5 minutes at 150 C.), washedthoroughly, framed, and dried. Data relating to the fabric samplestreated by this technique of padding and acid-catalyzed curing aresummarized in Table XVIII.

TABLE XVIII (W+F) crease recovery Percent Found by analysis, percentangle, degrees Warp Pad tensile bath Reagent, Moisture Corr. wt.EtIiciency of Bound strength,

Sample p OWF regain gain utilization N S CHzO Dry Wet pounds and Bwithout any treatment. The results are summarized Example 20 in TableXV.

TABLE XV Crease recovery (W+F), degrees Wet Dry Example 18 Example 17was repeated using an amine hydrochloride to provide acidic conditions.(The amine hydrochloride used was 30% aqueous solution made by the OnyxChemical Corporation, Jersey City, N.I., and sold under the 70 nameCatalyst XRF). The high temperature step was conducted at 150 C. and at163 C.

Data obtained on samples C and D are set forth in Table XVI. It is notedthat the higher temperature produced a larger amount of reacteddisulfide.

Cotton samples E, F and G, which were previously treated according tothe procedure of Example 17, were padded with 0.5 molar aqueous ammoniumthioglycollate (ATG) solution (pH adjusted to 9.0 by addition of amthenheated to C. for 2 minutes in a forced draft oven. The samples wererinsed in dilute acetic acid solution, then in water, finally framed anddried at 60 C.

A portion of each of samples E, F and G was then immersed for 5 hours ina 0.05 N iodine solution buffered to pH 7. After this period ofimmersion the samples were rinsed first in water, then in 3% sodiumthiosulfate solution for 1 hour, and finally in water. The portions werethen framed and dried at 60 C.

The ATG treatment was intended to show the reversibility of-thedisulfide linkages by conversion to mercapto groups. Table XIX indicatesfor samples E, F and G, the mercapto content after ATG treatment. Theiodine treatment was intended to oxidize the mercapto radicals andconvert, them to disulfide, thus reversing the character of the sulfurportion of the reactant. Table I indicates that the iodine treatmentlowered the percentage of mercapto radicals in the fabric, as expected.

tionsthe magnesium chloride used in Example 17 and the aminehydrochloride used in Example 18.

The samples were impregnated using a laboratory padder and setting therolls at a pressure to give 95-100% wet pick-up.

The fabric samples so treated were framed to the original size, dried at60 C. and heated to 160 C. for 4 minutes in a forced draft oven. Thesamples were rinsed in a 1:1 dimethylformamide-water mixture and washed1( with non-ionic detergent. The samples were then framed TABLE XIX tooriginal dimensions and dried.

Percent Mercapto Content Tab1e XXII shows data obtained on samplestreated with a solution contaimng 6.0% of a commercial buffered SampleAfter ATG Jame magnesium chloride solution.

1.42 0. 50 L02 M3 15 TABLE XXII 1 Percent Crease recovery (W+F) degreesDisulfide Weight The effects of the ATG and iodine treatments on thesample msohmon mama Ywld Wet crease recovery of samples E, F and G areshown in 20 I go 2.2 4% 257 19 Table XX- 1.. 0 4.1 42 264 18.

TABLE XX Crease recovery (W+F), degrees Before AT G After AT G Afteriodine treatment treatment treatment Percent weight Sample Dry Wet DryWet Dry Wet increase 267 270 226 230 242 24s 7. 259 264 220 227 24s 24s5. 2 24s 248 186 207 227 239 a. 0

Example 21 Example was repeated on sample H to provide a 5.0% weightincrease. However, instead of using iodine for the oxidation, the samplewas exposed to humid air (65 F., 70% RH), after the ATG treatment. TableXXI shows crease recovery measurements made on sample W.

TABLE XXI Crease recovery (W+F), degrees Dry Wet Before AT G treatment255 258 After AT G treatment, immediately- 198 216 After 24 hours 229234 Ater 48 hours 236 232 From the increase in crease recovery, it isapparent that humid air is sufiicient to reoxidize the mercapto groupsTable XXIII shows data obtained on samples treated with a solutioncontaining 3.0% of a commercial amine hydrochloride solution.

An untreated control had a dry crease recovery (W+F, degrees) of 195 anda wet crease recovery of 165.

Example 23 Rayon challis samples N and P, which were previously treatedaccording to Example 22, were padded with 0.5 molar ammoniumtrioglycollate (ATG) solution (pH adjusted to 9.0 by addition ofammonium hydroxide), using a laboratory padder and setting the rolls ata pressure to give 90100% wet pickup. The fabric samples so treated wereframed to the original size and dried at 60 C., then heated to 150 C.for 2 minutes in a forced draft oven. The samples were rinsed in diluteacetic acid solution, then in water, finally framed and dried at 60 C.

A portion of each sample was exposed to humid air F., RH).

Data obtained on the samples are set forth in Table formed during theATG treatment. XXIV.

TABLE XXIV Crease recovery (W+F), degrees Percent t ifafsni r i t tr tni lt a i r xgo s Sample in fe e Dry Wet Dry Wet Dry Wet 3:5 523 l3? $331 82 ZZZ 318 Example 22 70 Example 24 Viscose rayon fabric (commonlyknown as rayon challis) samples were treated with a disulfide producedas described in Example 1. The disulfide was dissolved in a 1:1 byweight dimethylformamide-water solution. Two

The procedural details of Example 19 were followed, except that thereagent was dithiobis[N- (hydroxymethyl) acetamide, and the actual pHvalues of the pad bath were different materials were used to provideacidic condi- 7 slightly difierent from those of Example 19. Datarelating 21 to the fabric samples so treated are summarized in theaccompanying Table XXV.

22 acterization, a portion was treated with hydrogen peroxide as perExample 15. Data on the products resulting from TABLE XXV (W+F) creaserecovery Percent Found by analysis, percent angle, degrees WarIp tensi eReagent, Moisture Corr. wt. Efiiciency oi Bound strength,

OWF regain gain utilization N S CHzO Dry Wet pound EXAMPLE A sample offabric resulting from treatment similar to this series of reversiblereactions are summarized in Table XXVIII.

TABLE XXVIII W+F crease recovery Warp angle, tensile N S strength., Per-Per- Sample Form Dry Wet lbs. cent cent 0 Mainly thiol 208 281 D.-Disulfide.. 230 269 31 0.48 1.33 E Thiol 204 189 31 F Disulfide 229 26933 that of Example 19 was immersed in 0.2-normal sodium 30 Example 27hydroxide for 30 minutes at room temperature with the fabric-to-liquorratio at 1-to-30 by weight. Processing steps resembled those describedin Example 4. The resulting product comprised mainly the thiol form withsome pendant CH NHCOOH CH SO H and groups. Data are summarized in TableXXVI. Inasmuch as both reduced and oxidized forms of the starting mate-The crosslinked product of Example 25 (Sample B) was treated withtetrakis(hydroxymethyl)phosphonium chloride using a procedure similar tothat described in Example 8. The product was characterized (as shown inTable XXIX) and then a portion of it was treated as described in Example5 with hydrogen peroxide. The reversible cycle was repeated twice more.Data are sum marized in Table XXIX.

TABLE XXIX W+F crease recovery Warp angle, deg. tensile PercentStrength, Dry W lbs. N Total Thiol 266 280 32 0. 1. 92 None 165 284 248258 164 210 225 251 167 224 226 243 rial are formed, this cleavage ofthe disulfide is known as Example 28 disproportionation. 55 A sample ofcross-linked fabric resulting from treat- TABLE XXVI W+F crease recoveryWarp angle, Deg. tensile Percent strength., Sample Form Dry Wet lbs. N S

EXAMPLE 26 ment similar to that of Example 24 (Sample A) was im- Themainly thio product of Example 25 (Sample C) was treated with hydrogenperoxide using conditions similar to those described in Example 5. Theresulting crosslinked product was characterized (as shown inaccompanying Table XXVIII) and then a portion of it was immersed in0.2-normal soidum hydroxide according to the procedure described inExample 25. Again, after charmersed in 0.2-normal sodium hydroxide for30 minutes 0 at room temperature with the fabric-to-liquor ratio at1-to-30 by weight to produce the predominantly thio form (Sample B).Processing steps resembled those described in Example 4. Then the fabricwas treated with hydrogen peroxide using conditions similar to thosedescribed in Example 5 (Sample C). Then a portion of Sample C wasimmersed in 0.2-normal sodium hydroxide according to the proceduredescribed in Example 25, to give Sample D, a portion of which wastreated with hydrogen peroxide as per Example 5, to give Sample E.

In another series, another sample resulting from treatment similar tothat of 'Example 24 (Sample G) was treated wtihtetrakis(hydroxymethyl)phosphonium chlo- 24 tion contained 2.0% of theamine hydrochloride solution used in Example 18.

The data obtained on samples U, V, W and X are set forth on Table XXXIIIbelow:

TABLE XXXIII Crease recovery (W-l-F) ride using a procedure similar tothat described in Ex- Percent degrees weight Percent ample 8 to producethe thiol form (Sample H). Then a Sample increase yield Dry Wet portionof it was treated in a manner similar to Example 10 4.0 51 236 186 5with hydrogen peroxide to form cross-linked Sample I. 5.3 68 237 182 Thereversible cycle repeated twice more (Samples K-N 5 :3 $2 3%; 133 Dataon these two series of samples are summarized in Table XXX. N OTE: Thesulfur content of sample X after the treatment was 2.5%.

TABLE XXX W+F crease recovery Warp 8 angle, deg. tensile strength, N,Total Thiol Sample Form Dry Wet, lbs. percent percent percent ADlsulfide 289 229 38 0. 89 2.25 None B Thiol (mainly) 212 257 40 0.45 CDisfllfide 261 280 36 0.73 1.63 0.06 D Thiol- 183 237 34 0. 23 EDicnlfidn 239 255 31 None G .do 289 229 38 0.89 2.25 None H Thiol 194230 39 0. 65 1.68 1.30 J Dienlfida 264 215 38 0. e 1. s9 0. 41 K Thiol186 229 38 0. 75

L Disnlfi do 245 256 31 0. 55 1.15 None M 169 22c 33 0. 58 N Disulfide231 21s 29 0.44 0. 24 None l 29 The sulfur content of sample X after thetreatment Plain weave cotton samples (commonly known as 80 X 80 printcloth) were treated with a disulfide having the following formula:

The disulfide was dissolved in a 1:1 by weight ethanolwater solutioncontaining magnesium chloride or amine hydrochloride, as described inthe examples above.

The fabric samples were impregnated using a laboratory padder with therolls set to provide 90-100 wet pickup.

The padded samples were framed and dried at 60 C. Samples Q and R werethen heated to 150 C. for 4 minutes in a forced draft oven. Samples Sand T were treated to 176 C. for 4 minutes in a forced draft oven. Thesamples were thoroughly rinsed and washed in dilute detergent solutionand framed and dried.

Table XXXI sets forth data on samples treated with a solution containing6.0% of the magnesium chloride solution.

TABLE XXXI Percent di- Percent sulfide in weight Percent Sample solutionincrease S actual Table XXXII sets forth data on samples treated with asolution containing 3.0% of an amine hydrochloride solution.

TABLE XXXII Percent di- Percent sulfide in weight Percent Samplesolution increase 8 actual Example was 2.5%.

It is to be appreciated that the specific examples set forth above areintended to be illustrative of the present invention and variations maybe made therein by one skilled in the art without departing from thespirit and scope of the present invention.

What is claimed is:

1. A compound having the following formula:

wherein R and R are each hydrogen or substituted or unsubstituted alkylhaving from 1 to 4 carbon atoms; R' is hydrocarbyl of 1 to 10 carbonatoms; W is a substituted or unsubstituted alkylene radical having 1 to4 carbon atoms, said substituted alkylene being alkylene containingoxygen in the form of a hydroxyl group or an ether linkage.

OTHER REFERENCES Martin et al.: Amides of N-acylcysteines as MucolyticAgents (1967), J. Med. Chem. 10 pp. 1172-1176 (1967).

Tesoro et al.: Reversible Crosslinks in Cotton Modified etc.; (1967),ACS Meeting, Apr. 11, 1967 J. Pol. Sci. 12 pp. 683-697 (1968).

LEWIS GOTTS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl.X.R.

260-327 R, 561 K, 561 S, 608, 609 R UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 2.686.258 mst 22. 1972 Inuentofls)oroslan. et a1 7 I It is certified that errqr' appears" in theabove-identified patent v and that said Letters Patent are herebycorrected as shown below:

Col. 3, line 83 "pregnetion" should read p1 eparation--; line 17,-"ineffected" should read --unafieg t ed;- l

01, .4, line 25, insrt. to-- before im Col. 6, lirie 23., insert -KC1 Qunder the arrow; line'65, "'collulosic" should read --cellulosic--. Y I

001 1610, Table I, under 8 in "Found" ,co'lurrm, "3 1 6" should readCol. 11 Table III under "Dry" column; v 1 84"; should read 28 L-' line74, ',"after" should read under Col. 17, Table XIV, in heading "percentMgcl "soln.2" should read --soln.--; line 2 head". should read headedend"Disufide" should read --Disulfide- Cole 19, line #9, "W" should read--H--.-

cal, 21, line 71L, "soidum" should read --sodium--.

Signed and sealed this 20th da of March 1973 SEAL) Attest:

EDWARD -M FLETCHER JR I ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-105O (10-69) USCOMWDC 6031M,

I & U.. GQVERNMENT PRINTIKG OFFICE: 1959 9-366-134

